Improvement in photo-galvanography



: Ur nrizn STATES PATENT OFFICE.

PAUL EMILE PLAOET, or PARIS, FRANCE.

IMPROVEMENT m PHOTO-,GALVA'NO'GRAPHY.

' Specification forming part of Letters Patent No. 43,82l, dated August 9, 1864.

To all whom itvmag concern:

Be it known that I, PAUL EMILE PLACET, of Paris, in the Empire of France, have in-' vented certain new and useful Improvements in Engraving; and I hereby declare that the following is a full, clear, and exact description of the same.

Myinvention consists in new process for pro-. ducing,'without the artistic retouching of photographic impressions,ornamental designs, eu graved plates, &c., by means of divers manipulations or modu's operand i, in the manner as follows: A plate is coated with a substance which light renders insoluble. a stereo or other like plate or surface carrying the design to be engraved, (clich,) to the action of the light, and the portions not ati'ected by the light are then dissolved. The insoluble parts appear upon the plate in relief, a cast of which being taken and reproduced by galvano-plastic process produce an engraved plate of the drawing, whose lines, however, are, neither fine nor presenting the semi-tints possessed by the model. parts in which the semi-tints prevail the light does not render the coating insoluble throughout its whole thickness. The lines are therefore undermined by the dissolving agent, and are thus too frail to resist the washings attending the manipulations and are frequently carried off, together withthe soluble matter underneath. This will evidently not take place if a suitable support be given to the insulated face'and if the dissolving agent be caused to act upon the side opposite. In this way the subjectile will retain the semi-tints, and engraved plates may be produced therefrom from a cast by galvano-plastic process, which will have the fineness of the model-.' To carry this into efl'ect 1 proceed as follows: I take an impression on. a plate of glass of the clich? sought to be produced. On this impression or drawings I spread a coat of Judea bitumen or other like sensitive matter. I then expose .to the-light the glass side. When this is effected l plunge the plate in a mixture of naphtha and bcnzine. The parts rendered insoluble by the action of the light will constitute reliefs more or less pronounced, according to the length of time of exposure to light, the sensitiveness ot' the matter employed, and the nature of the cliche. J udea bitumen proaid of the engraver or of After it is dry it is exposed, under In the.

duces a very delicate engraving, but of little relief or depth. 1 therefore prefer to employ amixture of gelatine with bichromate' of potassa or ammonia. lfon dissolving the soluble portion it is found that the reliefs are insufficient or too transparent, they may be increased by applying another coat of the sensitive matter, or by opcratingotherwise. iu the same manner as at first.

" This process is also applicable to the production of engraved plates, as described,froin engravings or prints from engraved plates on paper. The paper should then be made transparent and impervious to the dissolviugagents. Thus when bitumen is used as the sensitive matter with which the plate is coated the paper is first rendered impervious by dipping it in a solution'ofge'latine, gum, dextriue, orother like substance.

The operations must be varied according to circumstances. For producing engraved plates without directly operating on a proof or print the coating is applied to a thin plate of glass, gelatino, mica, horn, or other transparent body, and the plate is acted upon by the luminous rays on the side of the support. 7

The coagulation thus proceeds from the face which is in contact with the support, and the desiginafter washing, remains a fixture on the supporting medium.

Another mode of proceeding is as follows: On a plate of glass two or more coats of collodion, then a coat of bichromated gelatinc, are spread. After dryingthe same the borders of the gelatine are out. It is then easily detachable, carrying with it the collodiou, which forms body withit. l The plate thus prepared is exposed to light under a. clich on the collodionized side, a plate of metal coated with some adhesive substance is applied to it, and the two are passed through a pair of rollers of a rolling-press. The sheet is then united with the plate while the gelatinizetl plate which is not impressioued is in the proper condition to be operated upon by the dissolving agents. A single coat of collodion does not suffice to secure easy detachment of the sheet;- but instead of the collodion other substances having analogous properties may be used. After insulation, in order to give greater adherence of the collodion to the subjectile, it is preferred to spread a coat of va'rnish upon the 00110 dion. x

vis put on; or a metal minous, glutinous, which are sensitive when combined with other salts-suchas salts ofgold, silver,uraue,chrome,iron,su-lphurets,

Another mode ofi-proceedingis, estra nts I A thi 'but" levjelgs'urfa'ced plate of metal is covered with the sensitive compound-say bichromated gelatine. After drying a coat of collodion is applied and the plate is exposed to the sun under a clich. 5 .Aj'reshicoatoficolf lodion mixed with varnish, or a coat of'varnish alone, is then vapplied and 'finally a eoating (sixteenth of an 'inehthick) ofwa x and-resin disk is stuck on, as in the preceding case. After cooling, the thin metal plate is easily ideta'ched,"leaving the sheet of g'elatine to adhere to the subjectile with the insulated face-above. OtherwiseIprocoed-as" in theprecediii g case'q lhe first' coat of co'llodion would penetrate thegelatine with less uniformity it applied after insulation, be-- causethe-light renders *theparts Iattacked less .pervious.

:for its, object to maiutainthe engraving upon -.a .solid aml1evenfoundation by preventing The coatingof wax and resin has the 'collodion to work, and thus to disfignrei .thedesign. .Theewaxand-resin m-ay,h.owever, 1 be dispensed with by combining several coats -wotTcollodion. and varnish,l-so as neutralize Ti :the effects of contractionaud-expansion-of the rsubjectilei .Thedissolving-agent, acting-uponz j the non-insulated side, commences by swelling: :ythe parts n'ot impressioned and produces very 1 beautiful and sharp reliefs. these reliefs-may beutilized. Awcast' may be i .taken from them after the molding, before re. 2. ferred .to, inasmuchas nothing prevents the 1 action of the dissolving agent, in order tool taina second engraving, which would be the.

im'erse of the first. tive mattermay produce two engravings, one

by'the swelling of thepartsnon-impressioned, the other i ln'lieu of the two substances before referred to'-t0 wit, J ndea bitumen and bichroma ted gelatine-many vegetable andauimal matters In: many cases n Thus one coat of sensiby dissolving the parts less soluble.

may be used-such as resinous, gummy,albuand otherjjkesubstances to light-eitlier alcneor 7 if not impossible,

TlO thelight,in v operations, and the production of reliefsor plates engraved in int-aglio by molding orgal- 1 vano-plasty, substantially'as herein described -1 odurets, .tartaric acid; oxalicacid,}=sal-ammo- The operations are simplified by the employment of substances which, in'thefirst place, are insoluble and become-soluble 'nnder the action of' -vlight. There are man'ysubstances that possess this property. It is unnecessary, to enumerate them; but I may mention mixturesof' gelatine, or gum, or albumen with a salt of iron, together with tartaric acid, If either of these mixtures be used, the salt of iron should be entered to its maximum, In the latter case the dissolving agent comm'encesits action on theinsulated face and corrodes very much in the same manner as the acid, does injtheetchiug process, but with this, adw'antage, thatthe lines produced by the dissolving. agent are. more accurately defined and producean intensityor shade corresponding to the cliche. I v

If int-thecompositionof the sensitive coat t certain. yitrifiablensubstauces are introduced as: ingredients, audit" these are. caused; to ad- --.l iere :to t the reliefs afte'r. itlieirformation, enam' eled surfaces may bet-produced, p y u Upon the relief-surfaceprinting or fatink may be distributed, and the relief maybe then dissolved, and-the ink may be transferred on a stoneorzinc,whichinay then be operated upon by the processtof lithography.

Having tlirisrlescri-be l my inventionfl claimt The method of producing engraved surfaces by employment and application of substances which light renders insoluble to and upon the side of. the subjectilewhich is directly exposed combination with the dissolving In testimony whereof I have. signed my name to thisspeci fication before two su bscribiugwitnesses. Y o

' P. EM. PLAOET; Witnesses:

a E. JAUME,

1 Susanna GoULD, 

